Answer
The solution set is $\left\{-5, 5\right\}$.
Work Step by Step
Add $100$ to both sides:
\begin{align*}
4x^2-100+100&=0+100\\
4x^2&=100
\end{align*}
Divide $4$ on both sides to obtain:
$$x^2=25$$
Take the square root of both sides to obtain:
\begin{align*}
\sqrt{x^2}&=\pm\sqrt{25}\\
x&=\pm5
\end{align*}
Thus, the solution set is $\left\{-5, 5\right\}$.
